1. Field of the Invention
The present invention relates to a magnetic transfer apparatus for use in performing magnetic transfer from a master carrier bearing an information to a slave medium.
2. Description of the Prior Art
Generally, a master carrier (patterned master) for magnetic transfer comprises transfer patterns such as servo signals in the form of surface irregularities or embedded structure, with at least a soft magnetic layer on a surface layer. Such a master carrier comes into close contact with a slave medium having a magnetic recording part and, and a magnetic field for transfer is applied, whereby magnetic patterns corresponding to information carried on the master carrier are transferred to and recorded on the slave medium. Such technologies are disclosed in Japanese Patent Laid-open Publication No. Sho. 63-183623 and Nos. Hei. 10-40544 and 10-269566, and Japanese Patent Laid-open Publication No. 2001-256644 and the like.
In cases where the slave medium is a disk-shaped medium such as a hard disk or high-density flexible disk, a transfer magnetic field is applied by a magnetic field application means including an electromagnet device or permanent magnet device which is disposed at one side or both sides of the slave medium, in a state that the disk-shaped master carrier is kept in close contact with a single surface or both surfaces of the slave medium.
With the intention of increasing transfer quality, it is important that the whole surface of the slave medium comes into close contact with that of the master carrier. In case of poor contact, poor recording sectors which are not magnetically transferred are formed. In such a case, some signals are missing from magnetic information transferred to the slave medium, thus decreasing signal quality. In particular, when the recorded signals are servo signals, tracking function is deteriorated, thereby lowering reliability.
As for such magnetic transfer, a plurality of slave media are sequentially subjected to magnetic transfer by a single master carrier. Hence, it is preferred that the master carrier is set in the holder of the magnetic transfer apparatus and then the slave medium is conveyed to a contact position with the master carrier, thus bringing the slave medium into close contact with the master carrier, to which a transfer magnetic field is applied. At that time, for correctly positioning the master carrier or the slave medium to be seated evenly in a flat inner surface of the holder, the above elements may be kept in the state of being sucked to pressure-reducing suction parts. For example, in case where the master carriers come into close contact with both surfaces of the slave medium to simultaneously perform magnetic transfer to the both surfaces of the slave medium, two master carriers may be set to both inner surfaces of the holder. Alternatively, when the master carrier comes into contact with a single surface of the slave medium to sequentially perform magnetic transfer to the single surface of the slave medium, the master carrier may be positioned in any one inner surface of the holder and, as necessary, the slave medium may be set in the other inner surface of the holder. Further, when the slave medium is directly set to the master carriers, the slave medium need not be separately held.
In order to increase the extent of contact between the slave medium and the master carrier, a close contacting force may be applied to bring the slave medium into close contact with the master carrier. Additionally, with a view to removing air remaining on contact surfaces of the slave medium and the master carrier by suctioning air on the contact surfaces of them, a vacuum is created in an inner space of the holder. Further, it is considered that close contacting force may be provided by vacuum suction of the inner space.
As for aforementioned magnetic transfer, on the assumption that the movement of both inner surfaces of the holder toward and away from each other for bringing the slave medium into close contact with the master carriers in the holder is controlled separately from the vacuum suction of the inner space of the holder, before the slave medium comes into close contact with the master carriers to cause close contacting force, a vacuum condition is created in the inner space of the holder to reduce the pressure therein, thereby resulting in that air on contact surfaces of the slave medium and the master carriers is removed and the surfaces may come into mutual contact with one another. Accordingly, the extent of contact of the slave medium with the master carriers may be increased.
However, the process as stated above suffers from the following disadvantage. That is, attributable to the vacuum condition of the inner space of the holder before the slave medium comes into close contact with the master carriers to cause close contacting force, the master carriers or the slave medium kept in the state of being sucked to pressure-reducing suction parts in the holder may be decreased in suction force, and may be detached from the pressure-reducing suction parts. Namely, pressure difference between suction pressure of the pressure-reducing suction parts and pressure of the inner space becomes small due to reduction of pressure of the inner space. Further, suction force of the pressure-reducing suction parts becomes decreased, and there is no difference in pressure between the pressure-reducing suction parts and the inner space. Consequently, the master carriers or the slave medium are detached from the pressure-reducing suction parts and magnetic transfer cannot be performed, or the master carriers or the slave medium may be damaged so that it cannot be used. Even though the above elements are not detached, the master carriers or the slave medium may become misaligned, thus being incapable of recording transfer signals to desired positions.